Recursive C++ Program to Convert a Decimal Integer into Binary Number

Here is a very simple and recursively written C++ program to convert a decimal integer number into its binary equivalent. However it returns the binary equivalent in the form of a string of characters but you can very easily write an other function to convert this string into an actual binary number as well.

#include <iostream>
#include <string>
using namespace std;

//takes an integer as an argument and
//returns its binary equivalent in the
//form of a string of characters
string dec_to_binary(int);
////////////.............\\\

int main()
{
	int number;
	cout << "Enter a decimal number to convert it into a binary number:n";
	cin >> number;
	cout << dec_to_binary(number) << endl;
	system("pause");
	return 0;
}

string dec_to_binary(int num)
{
	if (num==0)
		return "0";
	else if (num==1)
		return "1";
	else if (num<0)
		return "-"+(dec_to_binary(-num));
	else
		return (dec_to_binary(num/2)+static_cast<char>((num%2)+48));
}

If you want me to explain any part of this program or have suggestions to improve it then please tell me via comments. I will try my best to respond promptly.